THE OCCULTATION OF SAO-78505 BY JUPITER

On 13 December 1989, Jupiter occulted a star with visual magnitude 8.7 and an estimated K magnitude of 7. We observed the event from Kitt Pe ak, Arizona, using a 64 x 64 infrared camera at a wavelength of 2.16 m u m. The resulting data on refractive defocusing of the stellar signal give information on the temperature of the jovian atmosphere at press ures similar to 2 to 10 mu bar, at near-equatorial latitudes. These ar e the first new stellar-occultation data for the high jovian atmospher e since the widely observed occultation of beta Sco A and C in 1971. B ecause of improvements in instrumental capability, our data are compar able to the best beta Sco A data though the star is six magnitudes fai nter. We derive a mean atmospheric temperature of 176 +/- 12 K on a le vel surface corresponding to an equatorial radius of 71,880 km and a p ressure of 1.8 mu bar at a jovicentric latitude of 8 degrees. This res ult complements the beta Sco results by providing improved precision a t low jovicentric latitudes where the fainter star beta Sco C was used in 1971. (C) 1995 Academic Press, Inc.